15. the ratio pv to nrt is plotted against pressure for ch4 at 0°c and 200°c. why does the curve for 0°c drop below the horizontal line for an ideal gas whereas the curve for 200°c does not?
a) at 200°c, the molecules can overcome intermolecular attractions.
b) at 200°c, the volume of individual molecules becomes negligible.
c) at 200°c, the forces between molecules become repulsive.